Ray tracing: convex and concave lensकिरण आरेख: उत्तल और अवतल लेंसRay tracing: convex and concave lens
NCERT Fig 9.17 · Class 12 Physics · Chapter 9 · interactive diagram
Parts and what they mean
- Convex (converging) lens (उत्तल (अभिसारी) लेंस) — Thicker in the middle; f is positive.
- Principal axis (मुख्य अक्ष) — Line through the optical centre O and the foci.
- First focal point F (प्रथम फोकस बिंदु F) — On the side of the incoming light, at distance f from O.
- Second focal point F′ (द्वितीय फोकस बिंदु F′) — On the far side, at the same distance f. Parallel rays converge here (convex).
- Optical centre O (प्रकाशिक केंद्र O) — A ray through it goes straight on, undeviated. All distances are measured from O.
- Object AB (वस्तु AB) — u is negative (left of O).
- Concave (diverging) lens (अवतल (अपसारी) लेंस) — Thinner in the middle; f is negative. Always forms a virtual, erect, diminished image of a real object.
- Ray parallel to the axis (अक्ष के समांतर किरण) — After refraction it passes through the second focus F′.
- Ray through the optical centre (प्रकाशिक केंद्र से किरण) — Goes straight through without deviation.
- Ray through the first focus F (प्रथम फोकस F से किरण) — Emerges parallel to the axis.
- Ray parallel to the axis (अक्ष के समांतर किरण) — Diverges as if coming from the first focus F (dashed extension).
- Ray through the optical centre (प्रकाशिक केंद्र से किरण) — Undeviated.
- Ray aimed at the second focus F′ (द्वितीय फोकस F′ की ओर किरण) — Emerges parallel to the axis.
- Real, inverted image (वास्तविक, उलटा प्रतिबिंब) — Rays actually meet: v > 0, m < 0 (m = v/u).
- Virtual, erect image (आभासी, सीधा प्रतिबिंब) — On the same side as the object: v < 0, 0 < m < 1.
Original diagram drawn by Simple Learning Hub, based on NCERT Fig 9.17. Report a mistake